U.S. patent application number 16/957520 was filed with the patent office on 2021-06-03 for signal monitor.
This patent application is currently assigned to HEWLETT-PACKARD DEVELOPMENT COMPANY, L.P.. The applicant listed for this patent is HEWLETT-PACKARD DEVELOPMENT COMPANY, L.P.. Invention is credited to James M. GARDNER, Scott A. LINN.
Application Number | 20210162745 16/957520 |
Document ID | / |
Family ID | 1000005448697 |
Filed Date | 2021-06-03 |
United States Patent
Application |
20210162745 |
Kind Code |
A1 |
LINN; Scott A. ; et
al. |
June 3, 2021 |
SIGNAL MONITOR
Abstract
An integrated circuit is disclosed. The integrated circuit
includes an actuator to eject a fluid in response to a fire signal.
The integrated circuit also includes a monitor circuit set by the
fire signal to block the fire signal to the actuator circuit after
a selected duration.
Inventors: |
LINN; Scott A.; (Corvallis,
OR) ; GARDNER; James M.; (Corvallis, OR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HEWLETT-PACKARD DEVELOPMENT COMPANY, L.P. |
Spring |
TX |
US |
|
|
Assignee: |
HEWLETT-PACKARD DEVELOPMENT
COMPANY, L.P.
Spring
TX
|
Family ID: |
1000005448697 |
Appl. No.: |
16/957520 |
Filed: |
February 6, 2019 |
PCT Filed: |
February 6, 2019 |
PCT NO: |
PCT/US2019/016745 |
371 Date: |
June 24, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B41J 2/04573 20130101;
B41J 2/04586 20130101; B41J 2/04543 20130101 |
International
Class: |
B41J 2/045 20060101
B41J002/045 |
Claims
1-20. (canceled)
21. An integrated circuit, comprising: an actuator to eject a fluid
in response to a fire signal; and a monitor circuit to be set by
the fire signal to block the fire signal to the actuator after a
selected duration.
22. The integrated circuit of claim 21 wherein the monitor circuit
includes an analog timer.
23. The integrated circuit of claim 22 wherein the analog timer
includes a resistor-capacitor circuit.
24. The integrated circuit of claim 21 wherein the monitor circuit
is configured to indicate a fault in response to blocking the fire
signal.
25. The integrated circuit of claim 24 wherein the monitor circuit
is configured to indicate the fault by one of setting a register
corresponding with the monitor circuit and with a fault condition
signal output from the integrated circuit.
26. The integrated circuit of claim 21 including a fire pad to
receive the fire signal.
27. The integrated circuit of claim 26 wherein the monitor circuit
is operably coupled to the fire pad to receive the fire signal.
28. The integrated circuit of claim 21 wherein the monitor circuit
includes a timer that is started with the activated fire signal,
and a blocking circuit operably coupled to the timer to block the
fire signal from reaching the fluid actuator if the timer has
expired and the fire signal is not deactivated.
29. The integrated circuit of claim 28 wherein the blocking circuit
includes a latch and an AND gate.
30. The integrated circuit of claim 28 wherein the timer includes a
buffer.
31. The integrated circuit of claim 30 wherein the buffer includes
a resistor-capacitor circuit.
32. A printhead comprising an integrated circuit, the integrated
circuit comprising: an actuator to eject a print substance in
response to a fire signal; and a monitor circuit to be set by the
fire signal to block the fire signal from reaching the actuator
after a selected duration.
33. The printhead of claim 32 wherein the monitor circuit is
configured to indicate a fault of the integrated circuit in
response to blocking the fire signal.
34. The printhead of claim 33 wherein the fault is indicated by
setting a register corresponding with the monitor circuit.
35. The printhead of claim 33 where the fault is indicated with a
fault condition signal output from the integrated circuit.
36. The print head of claim 32 wherein the monitor circuit includes
a timer to meter the selected duration and a blocking circuit
activated by the timer to block the fire signal from the
actuator.
37. An integrated circuit, comprising: a fluid actuator to eject a
print substance in response to an activated fire signal; a timer
that is started with the activated fire signal; and a blocking
circuit operably coupled to the timer to block the fire signal to
the fluid actuator if the timer has expired and the fire signal is
not deactivated.
38. The integrated circuit of claim 37 wherein the blocking circuit
includes a latch and an AND gate.
39. The integrated circuit of claim 37 wherein the timer includes a
buffer.
40. The integrated circuit of claim 39 wherein the buffer includes
a resistor-capacitor circuit.
Description
BACKGROUND
[0001] Printing devices can include printers, copiers, fax
machines, multifunction devices including additional scanning,
copying, and finishing functions, all-in-one devices, or other
devices such as pad printers to print images on three dimensional
objects and three-dimensional printers (additive manufacturing
devices). In general, printing devices apply a print substance
often in a subtractive color space or black to a medium via a
device component generally referred to as a printhead. Printheads
can employ fluid actuator devices, or simply actuator devices, to
selectively eject droplets of print substance onto a medium during
printing. For example, actuator devices can be used in inkjet type
printing devices. A medium can include various types of print
media, such as plain paper, photo paper, polymeric substrates and
can include any suitable object or materials to which a print
substance from a printing device are applied including materials,
such as powdered build materials, for forming three-dimensional
articles. Print substances, such as printing agents, marking
agents, and colorants, can include toner, liquid inks, or other
suitable marking material that in some examples may be mixed with
other print substances such as fusing agents, detailing agents, or
other materials and can be applied to the medium.
BRIEF DESCRIPTION OF THE DRAWINGS
[0002] FIG. 1 is a block diagram illustrating an example integrated
circuit, which can be used to drive a plurality of actuators.
[0003] FIG. 2 is a block diagram illustrating an example fluid
ejection device that can include the example integrated circuit of
FIG. 1.
[0004] FIG. 3 is a block diagram illustrating an example monitoring
circuit that can be included in the integrated circuit of FIG.
1.
[0005] FIG. 4 is a schematic diagram illustrating an example
monitoring circuit of the example monitoring circuit of FIG. 3.
DETAILED DESCRIPTION
[0006] An inkjet printing system, which is an example of a fluid
ejection system, can include a printhead, a print substance supply,
and an electronic controller. The printhead, which is an example of
a fluidic actuator device or actuator device, can selectively pump
fluid through fluid channels, or eject droplets of print substance
through a plurality of nozzle assemblies, of which each nozzle
assembly can be an example of an actuator, onto a medium during
printing. Example nozzle assembly can include a resistor or
piezo-element to pump the fluid through a nozzle or fluid channel.
The nozzles of the nozzle assemblies can be arranged on the
printhead in a column or an array and the electronic controller can
selectively sequence ejection of print substance. The printhead can
include hundreds or thousands of actuators, and each actuator
ejects a droplet of print substance in a firing event in which
electrical power and actuation signals are provided to printhead.
In one example, a printhead can correspond with a color or print
substance on the printing system. A printing system employing a
subtractive color can include a printhead corresponding with a cyan
print substance, a printhead corresponding with a magenta print
substance, a printhead corresponding with a yellow print substance,
and a printhead corresponding with a black, or key, print
substance.
[0007] In order to eject a print substance from an actuator, the
actuator can be loaded with the corresponding print substance and
supplied with electrical power and actuation signals to select
activation of the actuator. The firing event is triggered when a
fire signal is applied to the loaded actuator to eject the print
substance. The actuators are subjected to a sequence of firing
events with a sequence of fire signals applied to the printhead as
the printhead is moved relative the medium during printing. Each
actuator can consume tens of milliamperes (mA) of current during a
firing event. The printhead often staggers the firing events in
each actuator and amongst actuators to reduce peak power
consumption during printing. The amount of electrical power
required to simultaneously fire all actuators on the printhead can
exceed a current limit of the printing device, which can reduce
print quality or cause substantial damage to the printhead.
[0008] This disclosure is directed to a circuit to reduce the
likelihood of the printhead over-energizing the actuators, which
could reduce print quality or cause substantial damage to the
printhead. The circuit is configured to detect a possible
over-energizing condition, such as if the fire signal is
unexpectedly activated, or held in a high state, from a short
circuit as a result of an errant print substance drop, metal flake,
or another error on the printhead or in a circuit supplying the
fire signal to the printhead. In one example, if the fire signal
remains activated for longer than a selected amount of time, such
as for longer than an expected amount of time to trigger a firing
event, the circuit can disable the fire signal to the actuators
and, in some examples, notify the electronic controller of the
printing system of a fault condition in the printhead.
[0009] FIG. 1 illustrates an example integrated circuit 100 that
can be included in a printhead system. The integrated circuit 100
includes an actuator 102 to eject a fluid, such as a print
substance, in a firing event that is in response to a fire signal
104. In one example, the fire signal can be provided from an
external source such as the electronic controller and received at
the integrated circuit 100 at an electrical connection, such as a
conductive contact pad. The integrated circuit also includes a
monitor circuit 106, which is set by the fire signal 104. The fire
signal 104 can be routed to the actuator 102 via the monitor
circuit 106. The monitor circuit 106 blocks the fire signal 104 to
the actuator 102 if the fire signal remains activated after a
selected duration. For example, the monitor circuit 106 blocks the
fire signal 104 from reaching the actuator 102 if the fire signal
104 remains activated for longer than the selected duration, such
as longer than an expected amount of time to trigger the firing
event. In one example, the monitor circuit 106 includes a timer
that is started with an activated fire signal 104, such as when the
fire signal is received at the monitor circuit 106. The fire signal
104 can be a logic signal having a selected voltage and current
when activated, such as at a logic 1 setting, and deactivated, such
as at a logic 0 setting. A plurality of fire signals can be
received at the integrated circuit 100 as a stream of electrical
pulses. If the fire signal 104 is deactivated before the timer
expires at the selected duration, the monitor circuit 106 can be
reset in anticipation of a subsequent fire signal. If the fire
signal 104 remains active at the expiration of the timer at the
selected duration, the monitor circuit 106 disables the fire signal
104 to the actuator 102. In one example, the monitor circuit 106
can including a blocking circuit to indicate a fault condition to
an electronic controller if the monitor circuit 106 disables the
fire signal, and disable the actuator 102 from subsequent firing
events.
[0010] FIG. 2 illustrates an example of an integrated circuit 200
that can be incorporated into in a printhead and include features
of the example integrated circuit 100. The integrated circuit 200
includes a monitor circuit 202 that can include a timer and a
blocking circuit. The monitor circuit 202 can receive a fire signal
204 as an input 206 and selectively pass the fire signal 204 as an
output 208. In one example, the integrated circuit is electrically
coupled to a conductive electrical connection, such as a fire pad
210 to receive the fire signal from an external source, such as an
electronic controller. In one example, the fire signal 204 is
activated with a waveform having a logic voltage, such as a logic
high voltage between about 1.8 volts and 15 volts, for a selected
amount of time, such as one microsecond. The fire signal 204 can be
deactivated with a logic voltage such as a logic low voltage of 0.0
volts or the reference voltage GND.
[0011] The integrated circuit 200 is configured to drive a
plurality of fluid actuators on actuator device 212 to eject a
plurality of print substance droplets. The integrated circuit 200
also includes a plurality of delay circuits on delay circuit device
214. Each of the delay circuits on delay circuit device 214
produces an output waveform similar to its input waveform but
delayed by a selected amount of time. The plurality of delay
circuits are coupled together in series on the delay circuit device
214. The delay circuit device 214 receives the fire signal 204 from
the output 208 of the monitor circuit 202. Each of the of the delay
circuits receives the fire signal 204 in series, and after a delay,
provides the fire signal 204 via an output to a corresponding fluid
actuator on the actuator device 212 trigger or actuate a firing
event in the fluid actuators. For example, a delay circuit of the
plurality of delay circuits is coupled in series to a successive
delay circuit of the plurality of delay circuits. The delay circuit
receives the fire signal 204, and after a local delay, provides the
fire signal 204 to a corresponding fluid actuator of the plurality
of fluid actuators and to the successive analog delay circuit. The
successive delay circuit receives the fire signal 204, and, after a
local delay provides the fire signal 204 to a corresponding fluid
actuator of the plurality of fluid actuators. The delay circuits in
the delay circuit device 214 can include digital circuits having
flip-flops driven with a continuously running clock signal or
analog delay elements receiving a bias current to affect the delay
to stagger the firing events. The bias current can be used to
finely adjust delay of the analog delay elements as well as adjust
delay for various print speed modes of a printhead system.
[0012] In this example, the integrated circuit 200 staggers the
firing events in the actuator device 212 from a single fire signal
204 to reduce peak power consumption in the actuator device 212
during printing. Rather than simultaneously actuate hundreds or
thousands of actuators in the printhead, the delay circuit device
214 may simultaneously actuate a dozen or so actuators in the
actuator device 212. In one example, firing events in the actuator
device 212 are staggered in the order of 100 nanoseconds apart with
a fire signal having a duration of approximately one microsecond. A
fire signal 204 that is activated longer than the prescribed amount
of time, such as a fire signal that has been held at the logic high
as a result of a short circuit in the printhead system or the
external source, can cause substantial damage to the printhead
system.
[0013] The monitor circuit 202 includes a timer to meter the
selected duration. The timer is started when a fire signal 204 is
received, such as when the fire signal 204 is received at the input
206. If the monitor circuit 202 is activated, the fire signal 204
is passed to the delay circuit device 214. If the fire signal 204
is deactivated before the timer expires at the selected duration,
the monitor circuit 202 can be reset in anticipation of a
subsequent fire signal. If, however, the fire signal 204 remains
active at the expiration of the timer at the selected duration, the
monitor circuit 202 blocks the fire signal 204 from reaching the
delay circuit device 214. Accordingly, the delay circuit device 214
is unable to provide the fire signal 204 to the actuator device 212
to trigger a firing event. The monitor circuit 202 also alerts a
fault condition circuit 216, which can be detected by an electronic
controller. In the example in which the duration of the fire signal
204 is one microsecond, the selected duration of the timer can be
set to expire between 2.5 microseconds and 6.0 microseconds.
[0014] FIG. 3 illustrates an example of an integrated circuit 300
that can be incorporated into in a printhead and include features
of the example integrated circuit 100. The integrated circuit 300
includes a monitor circuit 302 that receives an input fire signal
304 and provides an output fire signal 306 to an actuator, such as
via a delay element, to trigger a firing event to eject a fluid.
The monitor circuit 302 includes a timer that is set by the fire
signal to meter the selected duration and a blocking circuit to
block the fire signal from output 306 after a selected duration. In
the example, the monitor circuit 302 also receives an enable signal
308 that activates the monitor circuit 302. In one example, the
monitor circuit will block the fire signal from the output in the
absence, or deactivation, of the enable signal. In the example, the
monitor circuit 302 can pass the fire signal from the input 304 to
the output 306 regardless of the duration in the absence of the
enable signal 308. In the example, the enable signal 308 operably
dependent on a bit in a monitor circuit configuration register 310;
and if the register 310 is set with a particular logic bit, such as
1, the integrated circuit 300 can provide the enable signal 308 to
the monitor circuit 302 and allow the fire signal to pass through
the monitor circuit 302 if the fire signal is of a duration less
than the selected duration.
[0015] In the example, the monitor circuit 302, which is activated
with the enable signal 308, receives the fire signal from the input
304. The received fired signal causes the voltage level at the
input 304 to transition between logic levels, such as from logic
low to logic high, which starts the timer to expire at a selected
duration on the monitor circuit 302. If the fire signal transitions
between logic levels, such as from logic high to logic low, before
the timer expires, the timer can reset for the next firing event.
If the fire signal has not transitioned before the timer expires,
such as the fire signal remains at logic high, the blocking circuit
prevents the fire signal from reaching the output 306.
[0016] In this example, the monitor circuit 302 indicates a fault
condition with a fault condition signal at a fault output 312. The
fault output 312 can be operably coupled to the electronic
controller to provide the fault condition signal. In one example,
upon receipt of the fault condition signal, the electronic
controller can be configured to issue an error and stop the sending
of subsequent fire signals to the integrated circuit 300. In
addition, the fault condition can disable the integrated circuit
300 such as disable the actuator from ejecting fluid. For example,
the fault output 312 can reset the monitor circuit configuration
register 310. If the register 310 is reset with a particular logic
bit according to the fault output 312, such as 0, the register 310
can deactivate the enable signal 308 and block subsequent fire
signals at the monitor circuit 302 from reaching the output 306. In
order to unblock the monitor circuit 302, in this example, the
monitor circuit configuration register is again set with a logic
bit, such as 1, to provide the enable signal 308.
[0017] In one example, the electronic controller, upon receiving a
fault condition signal provided to the fault output 312, can also
read the monitor circuit configuration register 310 to determine
the nature of the fault condition. For instance, a printing system
may include a plurality of integrated circuits, such as integrated
circuit 300, that correspond with a plurality of printheads
serviced by an electronic controller. Each of the plurality of
integrated circuits may be coupled to a fault output. If the
electronic controller receives a fault condition signal at the
fault output, the electronic controller can read the monitor
circuit configuration register of each of the plurality of
integrated circuits to determine which of the plurality of
integrated circuits blocked a fire signal with its monitor
circuit.
[0018] In one example, the monitor circuit 302 can provide a
pulldown signal as the fault condition signal to the fault output
312. The fault condition signal can be received an interpreted by
electronic controller as the primary indication that a fault
condition has occurred in the integrated circuit 300. In one
example, the fault condition signal can be presented as a thermal
fault. (The printhead includes thermal diode sensors operably
coupled to the fault output 312 to generate a voltage that drops as
the integrated circuit gets warmer, and the electronic controller
can detect if that voltage falls below a threshold to indicate a
thermal fault.) A low voltage fault condition signal at fault
output 312 can be used to simulate a thermal fault, and the
electronic controller can halt the printing process. Additionally,
the electronic controller can poll the monitor circuit
configuration register 310 of the integrated circuit 300, or, in
the case of multiple printheads in the printing device, poll the
monitor circuit configuration register on all of the integrated
circuits, to determine the both the nature of the fault and the
corresponding integrated circuit that generated the fault condition
signal.
[0019] FIG. 4 illustrates an example monitor circuit 400, which can
be included monitor circuit 302 of integrated circuit 300. Monitor
circuit 400 can be constructed out of integrated circuit elements
that comprise logic elements such as gates, buffers, latches or
flip flops. Example monitor circuit 400 is one example of a monitor
circuit 302, and other configurations are contemplated. In the
example, monitor circuit 400 receives a fire signal at fire input
402 and receives the enable signal at an enable input 404, and can
output the fire signal at fire output 406 and output a fault
condition signal at a fault output 408. In the example, the fire
input 402 and enable input 404 are provided to the inputs of a NAND
gate 410. The enable input 404 is also provided to the reset input
RN of an SR NAND latch 412. The output of the NAND gate 410 is
provided to a timer 414. The output of the timer 414 is provided to
at set input SN of the latch 412. Latch 412 provides outputs Q and
QB. Output Q can provide a fault condition signal to output 408.
Output QB and fire input 402 can provided to AND gate 416, which
provides an output to fire output 406. In this example, the timer
414 is configured to start with a signal from the NAND gate 410 and
provide a signal to the set input SN of latch 412 after the
selected duration, and the latch 412 and AND gate 416 operate as a
blocking circuit 418 to block a fire signal from the fire output
406 if the fire signal is activated for longer than the selected
duration as determined by the timer 414.
[0020] In one example, the timer 414 can include an analog circuit
such as a resistor-capacitor circuit. The resistor-capacitor (RC)
circuit can receive the output of the NAND gate 410 to a weak P
transistor and a strong N transistor, which are operably coupled to
an inverter circuit. In this example, the timer 414 operates as a
delay buffer or an RC delay circuit. The output of the NAND gate
410 is provided as an output of the timer 414 after the selected
duration. The selection of the circuit elements in the RC circuit
can determine the length of delay of the signal input to the timer
414 to the output of the timer 414. In this configuration, the
timer 414 delays transitions from logic high to logic low, i.e.,
falling voltage levels, for the selected duration, which can be on
the order a few microseconds. Transitions from logic low to logic
high, i.e., rising voltage levels, are quickly passed through the
timer 414, on the order of a few nanoseconds.
[0021] Monitor circuit 400, including timer 414, are relatively
simple designs to save on die area, but are also subject to large
variations of timing from process, voltage levels, and temperature
of the circuit. In one example, the selected duration can vary from
2.5 microseconds to 6.0 microseconds, or longer. But the actuators
have been determined to sustain such durations of an activated fire
signal.
[0022] In the example of the monitor circuit 400 with the timer 414
configured with an RC delay circuit, the enable input 404 is at
logic high when the monitor circuit 400 is configured for normal
operation. If the enable input 404 is at logic high, the reset
input RN is also at logic high. A fire signal at the fire input 402
also provides a logic high to the NAND gate 410, and the input to
the timer 414 is logic low. The delay of the timer 414 on
transition from logic high to logic low is on the order of
microseconds. If the fire signal at the fire input 402 is
deactivated prior to the timer passing the logic low signal to the
latch 412, the delay of the timer on transition from logic low to
logic high is on the order of nanoseconds, so the signal to the set
input SN of latch 412 remains logic high and the latch 412 is
inactive. The output QB is at logic high and the fire signal passes
through the AND gate 416 to fire output 406. If the fire signal at
the fire input 402 is not deactivated prior to the timer 414
passing the logic low signal to the latch 412, the set input SN
transitions from logic high to logic low, and the output QB becomes
logic low. The fire signal does not pass through the AND gate 416
to fire output 406, and the fire signal is blocked in the monitor
circuit 400. In the example, the output Q become logic high, and
provides a logic high fault condition signal at fault output 408.
In one example, the fault output 408 can be operably coupled to the
set the monitor circuit configuration register 310 and the fault
output 312 on integrated circuit 300 to indicate a failure
status.
[0023] Although specific examples have been illustrated and
described herein, a variety of alternate and/or equivalent
implementations may be substituted for the specific examples shown
and described without departing from the scope of the present
disclosure. This application is intended to cover any adaptations
or variations of the specific examples discussed herein. Therefore,
it is intended that this disclosure be limited only by the claims
and the equivalents thereof.
* * * * *